Expectancy and Treatment Interactions: A Dissociation between Acupuncture Analgesia and Expectancy Evoked Placebo Analgesia

Department of Psychiatry, Massachusetts General Hospital, Charlestown, MA 02129, USA.
NeuroImage (Impact Factor: 6.36). 04/2009; 45(3):940-9. DOI: 10.1016/j.neuroimage.2008.12.025
Source: PubMed


Recent advances in placebo research have demonstrated the mind's power to alter physiology. In this study, we combined an expectancy manipulation model with both verum and sham acupuncture treatments to address: 1) how and to what extent treatment and expectancy effects - including both subjective pain intensity levels (pain sensory ratings) and objective physiological activations (fMRI) - interact; and 2) if the underlying mechanism of expectancy remains the same whether placebo treatment is given alone or in conjunction with active treatment. The results indicate that although verum acupuncture+high expectation and sham acupuncture+high expectation induced subjective reports of analgesia of equal magnitude, fMRI analysis showed that verum acupuncture produced greater fMRI signal decrease in pain related brain regions during application of calibrated heat pain stimuli on the right arm. We believe our study provides brain imaging evidence for the existence of different mechanisms underlying acupuncture analgesia and expectancy evoked placebo analgesia. Our results also suggest that the brain network involved in expectancy may vary under different treatment situations (verum and sham acupuncture treatment).

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    • "Without conditioned-expectancy enhancement, music had significantly higher measured positive expectancy and was most effective at decreasing pain, followed by sound over silence. Expected relief was boosted in the conditioning groups, however typical corresponding increases in analgesia [26], [36]–[38] were not observed – the significant changes in expectancy did not link to pain relief. Music was the most pain relieving irrespective of conditioning, with enhanced music expectancy adding no further analgesia. "
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    ABSTRACT: Music has pain-relieving effects, but its mechanisms remain unclear. We sought to verify previously studied analgesic components and further elucidate the underpinnings of music analgesia. Using a well-characterized conditioning-enhanced placebo model, we examined whether boosting expectations would enhance or interfere with analgesia from strongly preferred music. A two-session experiment was performed with 48 healthy, pain experiment-naïve participants. In a first cohort, 36 were randomized into 3 treatment groups, including music enhanced with positive expectancy, non-musical sound enhanced with positive expectancy, and no expectancy enhancement. A separate replication cohort of 12 participants received only expectancy-enhanced music following the main experiment to verify the results of expectancy-manipulation on music. Primary outcome measures included the change in subjective pain ratings to calibrated experimental noxious heat stimuli, as well as changes in treatment expectations. Without conditioning, expectations were strongly in favor of music compared to non-musical sound. While measured expectations were enhanced by conditioning, this failed to affect either music or sound analgesia significantly. Strongly preferred music on its own was as pain relieving as conditioning-enhanced strongly preferred music, and more analgesic than enhanced sound. Our results demonstrate the pain-relieving power of personal music even over enhanced expectations. Trial Information Clinicaltrials.gov NCT01835275.
    PLoS ONE 09/2014; 9(9):e107390. DOI:10.1371/journal.pone.0107390 · 3.23 Impact Factor
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    • "In this study we have adopted both sham acupuncture and wait list controls. Our aim for establishing those two groups is to differentiate and isolate the placebo effect and patient expectancy [47,48] in particular, to further validate the pure effect of acupuncture. "
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    • "However, it resembles a paradoxical finding in neuroscience: attempts to discriminate – on a central level - different modalities that induce analgesia to pain have found more similarities than differences in central activations and inactivations. This is despite the fact that there appear to be small but distinct differences, e.g. between acupuncture and placebo analgesia [38], and between the effects of hypnosis and other therapies of visceral pain [39], when investigated with functional magnetic resonance imaging. If, however, different psycho-physiological treatment modalities induce similar brain processes, it cannot be expected that peripheral physiological changes secondary to this central activation would be different. "
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    PLoS ONE 12/2013; 8(12):e83486. DOI:10.1371/journal.pone.0083486 · 3.23 Impact Factor
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